Magnetically biased electromagnet for audio applications

ABSTRACT

An electronic device having an enclosure having a top panel and a bottom panel. An electromagnet is mounted within the enclosure, the electromagnet having a core portion attached to the top panel and a coil connected to the core portion. An attractor plate is attached to the bottom panel, the attractor plate forming part of a magnetic circuit of the electromagnet such that when an electrical audio signal is applied to the electromagnet, the bottom panel vibrates and produces a sound. A permanent magnet is further attached to the core portion, the permanent magnet is configured to create a bias in the magnetic circuit so as to modify a distortion in the sound.

FIELD

An embodiment of the invention is directed to a biased electromagnet foraudio electronic devices. Other embodiments are also described andclaimed.

BACKGROUND

In modern consumer electronics, audio capability is playing anincreasingly larger role as improvements in digital audio signalprocessing and audio content delivery continue to happen. There is arange of consumer electronics devices that are not dedicated orspecialized audio playback devices, yet can benefit from improved audioperformance. For instance, portable computing devices such as laptops,notebooks, and tablet computers are ubiquitous, as are portablecommunications devices such as smart phones. These devices, however, donot have sufficient space to house high fidelity speakers. This is alsotrue to a lesser extent for desktop personal computers and low profiletelevision sets with built-in speakers.

Generally, as a speaker decreases in size it is able to move less volumeand thus sound quality (or at least loudness) may decrease. This may beespecially noticeable for sounds in the lower end of the audio spectrum,e.g., beneath 1 kHz. Furthermore, the available volume within anelectronic device shrinks, which in turn provides less air for a speakerto react against and thus limits the audible response. Similarly, thesound level and frequencies able to be produced by a speaker may alsodecrease as the size of the speaker decreases. Thus, as electronicdevices continue to decrease in size, detrimental effects may beexperienced for audio produced by the devices.

SUMMARY

An embodiment of the invention is an electronic device including anenclosure having a top panel and a bottom panel. An electromagnet ismounted within the enclosure, the electromagnet includes a core portionattached to the top panel and a coil connected to the core portion. Anattractor plate may be attached to the bottom panel. The attractor plateforms part of a magnetic circuit of the electromagnet such that theapplication of an electrical audio signal to the electromagnet causesthe bottom panel to move and produce a sound. A permanent magnet is alsoattached to the core portion, the permanent magnet is configured tocreate a bias in the magnetic circuit so as to modify a distortion inthe sound.

Another embodiment is directed to an electronic audio system includingan enclosure having a first panel operably connected to a second panel.A transducer is mounted within the enclosure. The transducer includes anelectromagnet having a core portion operably connected to the firstpanel and a coil operably connected to the core portion. The transducerfurther includes an attractor plate operably connected to the secondpanel, the attractor plate forms part of a magnetic circuit of theelectromagnet such that an electrical audio signal input to theelectromagnet creates a dynamic force between the first panel and thesecond panel so as to generate a sound. The transducer further includesa permanent magnet operably connected to the core portion, the permanentmagnet is configured to create a biased force between the attractorplate and the electromagnet so as to modify a distortion in the sound.The electronic audio system further includes a memory to store anoperating system program and a processor coupled to the memory toexecute the operating system program.

In another embodiment, a method of outputting sound from an electronicdevice is disclosed. The method includes generating a sound by producinga dynamic force between a first panel and a second panel of an enclosureof an electronic device. Producing the dynamic force may includeapplying an electrical audio signal to an electromagnet associated withthe first panel so as to create a magnetic circuit which attracts thesecond panel to the first panel. The method further including biasingthe magnetic circuit so as to modify a distortion in the sound.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and they mean at least one.

FIG. 1A is a cross-sectional side view of one embodiment of amagnetically biased electromagnet.

FIG. 1B is a bottom perspective exploded view of the magnetically biasedelectromagnet of FIG. 1A.

FIG. 2A is one embodiment of an audio signal waveform.

FIG. 2B is one embodiment of a rectified audio signal waveform.

FIG. 2C is one embodiment of a biased audio signal waveform associatedwith a sound produced by an electronic device within which amagnetically biased electromagnet is implemented.

FIG. 3 is a cross-sectional side view of another embodiment of amagnetically biased electromagnet.

FIG. 4 is a cross-sectional side view of another embodiment of amagnetically biased electromagnet.

FIG. 5 is a cross-sectional side view of another embodiment of amagnetically biased electromagnet.

FIG. 6A is a perspective view of one embodiment of an electronic devicewithin which the magnetically biased electromagnet may be implemented.

FIG. 6B is a block diagram of certain embodiments of the electronicdevice illustrated in FIG. 6A.

FIG. 7 is an exploded view of a bottom enclosure of the electronicdevice.

FIG. 8 is a perspective view of another embodiment of an electronicdevice within which the magnetically biased electromagnet may beimplemented.

DETAILED DESCRIPTION

In this section we shall explain several preferred embodiments of thisinvention with reference to the appended drawings. Whenever the shapes,relative positions and other aspects of the parts described in theembodiments are not clearly defined, the scope of the invention is notlimited only to the parts shown, which are meant merely for the purposeof illustration. Also, while numerous details are set forth, it isunderstood that some embodiments of the invention may be practicedwithout these details. In other instances, well-known structures andtechniques have not been shown in detail so as not to obscure theunderstanding of this description.

FIG. 1A illustrates a cross-sectional side view of one embodiment of amagnetically biased electromagnet. FIG. 1B illustrates an explodedperspective view of the electromagnet of FIG. 1A. Electromagnet 100 mayact as a transducer that can be used to produce a dynamic force betweentwo or more components in order to generate sound using an appliedelectrical current. In one embodiment, the components may be opposingpanels of an enclosure for an electronic audio device, for example, atop panel 106 and a bottom panel 108. Top panel 106 and bottom panel 108may be connected by sidewalls such that they can contain components ofthe audio device, for example, a keyboard housing of a laptop computer.

Electromagnet 100 may drive movement of top panel 106 or bottom panel108 with respect to the other in order to generate a sound. To do so, inone embodiment, electromagnet 100 may be attached to top panel 106 andan attractor plate 110 may be attached to bottom panel 108. In thisembodiment, electromagnet 100 and attractor plate 110 are separate andindependent structures which are separately attached to their associatedpanels. Attractor plate 110 may be a substantially planar structure suchthat it does not substantially affect a Z-height of the overallenclosure (e.g. a thickness or vertical height of the enclosure asviewed in FIG. 1A). In one embodiment, attractor plate 110 may be madeof a ferromagnetic material (e.g., iron) and mounted to a surface ofbottom panel 108 which faces electromagnet 100. A gap 112 may be formedbetween electromagnet 100 and attractor plate 110 such that they havespace to move vertically with respect to one another. Application of anelectrical audio signal to electromagnet 100 creates one or more ofmagnetic circuits 114A and 114B between electromagnet 100 and attractorplate 110. Magnetic circuits 114A and 114B create an attractive dynamicforce between electromagnet 100 and attractor plate 110 as illustratedby arrows 116 and 118. In one embodiment, top panel 106 is asubstantially stationary structure and bottom panel 108 is moveable. Inthis aspect, the attractive force pulls attractor plate 110 towardelectromagnet 100 and in turn pulls bottom panel 108 toward top panel106. In some cases, the entire bottom panel 108 moves, while in others aportion of the bottom panel 108 attached to attractor plate 110 bows outtoward electromagnet 100. Electromagnet 100 may be used to move thebottom panel 108 toward and away from electromagnet 100 such that bottompanel 108 serves essentially as a diaphragm which can be used togenerate a sound to enhance an acoustic performance of the associatedelectronic device.

It should be understood, however, that although electromagnet 100 isdescribed as being attached to a stationary top panel 106 whileattractor plate 110 is attached to a movable bottom panel 108, otherconfigurations are possible depending upon which of the associatedcomponents are to be moved. For example, in some embodiments, top panel106 may be movable while bottom panel 108 is stationary such that theelectromagnet 100 and attractor plate 110 move top panel 106 whilebottom panel 108 remains stationary. In another example, electromagnet100 may be attached to a movable panel (panel 108) while attractor plate110 is attached to a stationary panel (panel 106) such that the panelattached to electromagnet 100 moves while the panel attached toattractor plate 110 remains stationary. Also, although the terms “toppanel” and “bottom panel” are used herein, it does not necessarily meanthat one panel is on top of the other, and in some cases the bottompanel may form a top or side of the enclosure or the top panel may forma bottom or side of the enclosure, for example, where the electronicdevice is flipped over or flipped on its side. In addition, althoughelectromagnet 100 and attractor plate 110 are described as beingattached to top panel 106 and bottom panel 108, respectively, they maybe attached to any type of component or structure where movement of onewith respect to the other is desired.

It should further be understood that an advantage of using electromagnet100 and attractor plate 110 to produce a dynamic force between top panel106 and bottom panel 108, as compared to a typical moving coil design,is that the electromagnet 100 sits on one component (top panel 106 inthis case) and only a passive attractor plate 110 sits on the othercomponent (bottom panel 108 in this case). This allows the transducer tobe tolerant of relative positioning (e.g. horizontal positioning) of onecomponent with respect to the other. This is in contrast to a movingcoil configuration in which the magnet and the coil are attached toseparate components and therefore have to be accurately aligned in boththe horizontal and vertical directions.

Referring in more detail to electromagnet 100, electromagnet 100includes a core portion 102 and associated coil 120. Coil 120 may bemade of an electrically conductive material such that transmission of anelectrical current through coil 120 creates a magnetic field which canbe concentrated within core portion 102. In one embodiment, the coreportion 102 may include a base portion 122 which is a substantiallyplanar member which is mounted within the enclosure, on or near toppanel 106. A coil support arm 124 and side arms 126 and 128 extend frombase portion 122 in a direction of bottom panel 108. Side arms 126 and128 are spaced a distance from opposing sides of coil support arm 124such that coil 120 can be positioned around coil support arm 124.Although three arms are shown extending from base portion 122, it iscontemplated that core portion 102 may include any number of armssufficient to support the associated coil and allow for attachment of acomponent such as top panel 106. In some embodiments, core portion 102and the associated coil 120 are attached directly to top panel 106, suchas by a bolt, screw or the like through base portion 122, while in otherembodiments, a bracket assembly may be used to attach core portion 102and the associated coil 120 to top panel 106. Core portion 102 may beone integrally formed structure made of any material suitable forforming an electromagnet core (e.g., a ferromagnetic material such asiron).

In some embodiments, permanent magnets 104A and 104B are attached to theends of side arms 126 and 128, respectively, facing attractor plate 110.In one embodiment, side arms 126 and 128 may have a length which is lessthan coil support arm 124 so as not to increase an overall height ofelectromagnet 100 when permanent magnets 104A and 104B are attachedthereto. Such a configuration also helps to maintain the spacing of gap112 between electromagnet 100 and attractor plate 110. Permanent magnets104A and 104B are used to create a bias force between attractor plate110 and electromagnet 100. This bias force is important to the acousticperformance of the device because it allows the sound created bymovement of the bottom panel 108 to be accurately recreated from thedynamic input electrical audio signal without distortion. In particular,as previously discussed, electromagnet 100 creates an attractive forcewith attractor plate 110. Since only attractive forces are possible, theinput electrical audio signal is rectified and therefore anycorresponding dynamic force produced by the audio signal is notproportional to the audio signal (i.e. any audio signal current belowzero is output as a positive dynamic force). This, in turn, results in adistorted sound output.

The concepts of a bias force and rectification of the audio signal maybe better understood in reference to FIG. 2A, FIG. 2B and FIG. 2C. Inparticular, FIG. 2A illustrates an undistorted audio signal waveform 202in which the Y-axis represents the current (Amps) and the X-axisrepresents time. It can be seen that the current levels change with timeand alternate between positive values and negative values. In theabsence of the biased force created by permanent magnets 104A and 104B,these negative values are output as positive forces (i.e., rectified),thus distorting the sound. FIG. 2B illustrates the rectified dynamicforce waveform 204, which corresponds to audio signal waveform 202 whenthe bias force is not present. The Y-axis represents the force (N) andthe X-axis represents time. From waveform 204, it can be seen that whenforce (N) is greater than 0, as is the case when only attractive forcesare possible, the negative portions of audio signal waveform 202illustrated in FIG. 2A are rectified as shown in FIG. 2B and thus theaudio signal 202 is distorted. FIG. 2C illustrates the audio signal ofFIG. 2A when the biased force is created between attractor plate 110 andelectromagnet 100 by permanent magnets 104A and 104B. The biased force208, in this case approximately 1.5N, biases the signal waveform 206 ina positive direction so that the entire audio signal waveform 202 ofFIG. 2A is above zero and can therefore be recreated as a dynamic forcewithout the distortion. In other words, as a result of the biased force208, the dynamic force produced by the electromagnet is proportional tothe dynamic input audio signal. Although a bias force of approximately1.5N is illustrated, it is to be understood that any bias forcenecessary to reduce the distortions may be used. For example, the biasforce may be from about 0.5N to about 2.5N, for example, from about 1Nto about 1.5N.

With the foregoing in mind, the manner in which permanent magnets 104Aand 104B create the biased force and allow for the sound created bybottom panel 108 to be recreated from the dynamic audio signal withoutdistortion will now be described in more detail. Representatively,referring back to FIG. 1A, when an electrical audio signal is applied tocoil 120 of electromagnet 100 in a direction of arrow 130, magneticcircuits 114A and 114B are created. Magnetic circuits 114A and 114Bcreate an attractive force between electromagnet 100 and attractor plate110. This attractive force pulls attractor plate 110, and the associatedbottom panel 108, toward electromagnet 100. Permanent magnets 104A and104B are positioned within magnetic circuits 114A and 114B,respectively, such that sometimes the magnetic circuits created by coil120 are with (i.e., add to) the magnetic force created by permanentmagnets 104A and 104B and sometimes they are against (i.e., subtractfrom) the magnetic force of permanent magnets 104A and 104B. Whenmagnetic circuits 114A and 114B are with the magnetic force, the bottompanel 108 is pulled closer to the electromagnet 100, i.e., panel 108moves or bows in a direction of electromagnet 100. When the circuits114A and 114B are against the magnetic force, the bottom panel 108 ispulled less close to the electromagnet 100, i.e., panel 108 returns tothe resting, non-bowed or less bowed configuration. In either case,there is always a biased force between attractor plate 110 andelectromagnet 100 due to permanent magnets 104A and 104B such that thedynamic force, which drives movement of panel 108, is proportional tothe input electrical audio signal (as illustrated by FIG. 2C) andtherefore the resulting sound can be recreated without distortion.

It is noted that the distance the attractor plate 110, and in turnbottom panel 108, travel to or from electromagnet 100 may be varied byvarying the electrical charge to which coil 120 is subjected. In thismanner, attractor plate 110 may be driven by electromagnet 100 inprecise motions depending upon the strength and duration of theelectrical current applied to the coil. The motion of the correspondingpanel, in this case bottom panel 108, produces audible sound waves whichcan enhance an acoustic response of the overall audio device. Thus theattractor plate 110 in combination with electromagnet 100 essentiallyserves as a transducer in which bottom panel 108 operates similar to thediaphragm found in the conventional audio transducer.

In some embodiments, bottom panel 108 may produce audible low frequencysound waves (e.g., sound waves of below 1 kilohertz frequency) as wellas other audio frequency sounds. Bottom panel 108 may have a greatersurface area than a diaphragm of a typical speaker that may be containedwithin the electronic device, as such, it may move more air and thusproduce more (and possibly clearer) audio. That is, because the bottompanel 108 may have a larger surface area than other speakers installedwithin the electronic device, the sound produced by causing the bottompanel 108 to move may be louder than traditional speakers. Also, becausethe electromagnet 100 utilizes the whole enclosure to move most of theair, the actual size of the transducer assembly (i.e., electromagnet 100and attractor plate 110) may be quite small in comparison to atraditional speaker capable of outputting the same volume of audio. Thisis beneficial due to the limited space within typical electronic deviceenclosures. Thus, the transducer assembly may save space, whileproducing a loud sound often not achievable by ordinary speakers withinthe space constrains of the enclosure(s).

Returning now to the configuration of permanent magnets, in oneembodiment, permanent magnets 104A and 104B may be attached (e.g.,chemically attached, welded, screwed, or the like) to an end of sidearms 126 and 128, respectively, such that they face attractor plate 110and are within the magnetic circuit created by electromagnet 100.Permanent magnets 104A and 104B may be positioned such that their polesface the same direction. In other words, both permanent magnets 104A and104B are oriented so that their South poles face attractor plate 110 oreso that their North poles face attractor plate 110. Permanent magnets104A and 104B may extend along the entire length of side arms 126 and128 as illustrated by the exploded view of FIG. 1B. In otherembodiments, one or more of permanent magnets 104A and 104B may extendalong only a portion of the length of side arms 126 and 128. Permanentmagnets 104A and 104B may be made of any material suitable for formingpermanent magnets having the desired biasing force, for example, a hardferromagnetic material such as alnico or ferrite.

FIG. 3 illustrates a cross-sectional side view of another embodiment ofa magnetically biased electromagnet. Each of the aspects ofelectromagnet 100, attractor plate 110 and permanent magnets 104A, 104Billustrated in this view are substantially the same as those discussedin reference to FIG. 1A. In addition the previously discussed aspects,resilient spacers 302A, 302B and 302C are provided within gap 112between electromagnet 100 and attractor plate 110. Resilient spacers302A-302C may allow for more accurate vertical alignment ofelectromagnet 100 with respect to attractor plate 110 as well as allowsome relative misalignment in the horizontal direction. In addition,resilient spacers 302A-302C may create a push force betweenelectromagnet 100 and attractor plate 110. As previously discussed, theforce created between electromagnet 100 and attractor plate 110 is onlyan attractive or pull force. Resilient spacers 302A-302C may thereforeadd a push force which helps with movement of attractor plate 110 andthe associated panel 108 with respect to electromagnet 100. In thisaspect, resilient spacers 302A-302C may be dimensioned to fit within thegap 112 provided between electromagnet 100 and attractor plate 110 sothat a relatively consistent vertical spacing range may be maintainedbetween electromagnet 100 and attractor plate 110. In one embodiment,resilient spacers 302A-302C may be dimensioned so that they are alwaysslightly compressed between electromagnet 100 and attractor plate 110and more compressed when an electrical current 130 is applied toelectromagnet 100. In other words, when the electromagnet 100 andattractor plate 110 are in a rest position (e.g., applied electricalcurrent is zero), resilient spacers 302A-302C are slightly compressedsuch that they apply a push force which wants to push attractor plate110 away from electromagnet 100. In an actuated position (e.g.,electrical current is greater than zero), resilient spacers 302A-302Care compressed even further as attractor plate 110 is pulled towardelectromagnet 100 by the magnetic circuits 114A, 114B.

Resilient spacers 302A-302C may be attached to the ends of, and runalong an entire length of, each of side arms 126, 128 and coil supportarm 124. Alternatively, resilient spacers 302A-302C may run along only aportion of the arms, or be attached to less than each of side arms 126,128 and coil support arm 124 as illustrated. Still further, it iscontemplated that one or more of resilient spacers 302A-302C may beomitted such that they are attached to less than each of each of sidearms 126, 128 and coil support arm 124.

Resilient spacers 302A-302C may be made of any resilient structure ormaterial suitable for maintaining a vertical alignment and/or enhancingmovement between electromagnet 100 and attractor plate 110. For example,one or more of resilient spacers 302A-302C could be made of a block ofresilient or elastic material such as a rubber or foam material.Alternatively, resilient spacers 302A-302C could be made of a spring orother resilient structure. In some embodiments, resilient spacers302A-302C may contain a ferromagnetic material such that they help toimprove an efficiency of the magnetic circuit. Representatively,resilient spacers 302A-302C may be made entirely of a ferromagneticmaterial (e.g., an iron spring) or they may be made of a composite of aresilient material such as a rubber or elastic material which isembedded with or otherwise contains a ferromagnetic material (e.g.,filings) in an amount sufficient to improve the efficiency of themagnetic circuit.

FIG. 4 illustrates a cross-sectional side view of another embodiment ofa magnetically biased electromagnet. Each of the aspects ofelectromagnet 100 and attractor plate 110 are substantially the same asthose discussed in reference to FIG. 1A except that in this embodiment,permanent magnets 404A and 404B are attached (e.g., welded, bolted orthe like) along the side walls of side arms 126 and 128, respectively,of core portion 102. In this aspect, magnetic circuits 414A and 414B arecreated which extend outside of side arms 126 and 128 and throughpermanent magnets 404A and 404B. Permanent magnets 404A and 404B mayextend along the entire length of side arms 126 and 128 or only aportion of the side arms. In any case, permanent magnets 404A and 404Bmay have any shape or dimensions sufficient to bias magnetic circuits414A and 414B and modify a distortion in the audio signal as in themanner previously discussed.

FIG. 5 illustrates a cross-sectional side view of another embodiment ofa magnetically biased electromagnet. Each of the aspects ofelectromagnet 100 and attractor plate 110 are substantially the same asthose discussed in reference to FIG. 1A except that in this embodiment,permanent magnet 504 is attached (e.g., welded, bolted or the like) toan end of coil support arm 124 facing attractor plate 110. Permanentmagnet 504 may extend along an entire length of coil support arm 124 oronly a portion of coil support arm 124. In this aspect, magneticcircuits 514A and 514B are created which extend along side arms 126 and128 and through permanent magnet 504 as shown. Permanent magnet 504 mayhave any shape or dimensions sufficient to bias magnetic circuits 514Aand 514B and modify an acoustic distortion in the manner previouslydiscussed.

It is to be understood that although the previously discussed permanentmagnets are shown at specific locations along electromagnet 100, it iscontemplated that the permanent magnets may be positioned at anylocation within the magnetic circuit created by electromagnet 100.Moreover, a single permanent magnet may be positioned within themagnetic circuit or more than one permanent magnet may be positionedwithin the magnetic circuit, for example, three permanent magnets may bepositioned within the magnetic circuit, e.g., one at each end of arms124, 126 and 128. Moreover, although core portion 102 of electromagnet100 is shown having three arms 124, 126 and 128, any number of armssufficient to create a magnetic circuit between electromagnet 100 andattractor plate 120 may be provided. For example, more or fewer thanthree arms may extend from base portion 122. Representatively, in oneembodiment, two arms may extend from base portion 122 and coil 120positioned around one of the arms or the base portion between the arms.In another embodiment, the arms may be omitted and coil 120 may bepositioned around the base portion 122.

In addition, it is contemplated that in some embodiments attractor plate110 may be omitted and instead, the enclosure opposite the electromagnet100 and coil 120, which is used to generate the sound (e.g., bottompanel 108), may be made of a material similar to attractor plate 110(e.g., a ferromagnetic material). In this aspect, the attractive forcecreated by electromagnet 100 pulls the enclosure panel towardelectromagnet 100 in the absence of attractor plate 110.

In another embodiment, the bias force between electromagnet 100 andattractor plate 110 may be created by using a direct current (DC) (i.e.,bias current) to create the bias instead of permanent magnets and thepermanent magnets may be omitted. Representatively, the audio signal maybe tracked and the bias signal varied slowly over time such that only asufficient bias is used in a given section of the audio signal (e.g., adesired section of a song) to stop the force from dropping to zeroresulting in signal rectification.

FIG. 6A illustrates a perspective view of one embodiment of anelectronic device in which the biased electromagnet described herein maybe implemented. FIG. 6B illustrates a block diagram of one embodiment ofthe electronic device of FIG. 6A. Electronic device 600 may include atop enclosure 614 and a bottom enclosure 612. The enclosures 612, 614generally surround or enclose the internal components of the electronicdevice 600, although apertures and the like may be formed into one orboth of the enclosures. The electronic device 600 may include a keyboard618, a display screen 616, a speaker 620, and optional feet 622. Also,the electronic device 600 generally includes an audio transducerassembly 626 (i.e., magnetically biased electromagnet and attractorplate), as shown in FIG. 7, encased within or affixed to one or both ofthe enclosures 612, 614.

Electronic device 600 may be capable of storing and/or processingsignals such as those used to produce images and/or sound. In someembodiments, electronic device 600 may be a laptop computer, a handheldelectronic device, a mobile telephone, a tablet electronic device, anaudio playback device, such as an MP3 player, and the like. A keyboard618 and mouse (or touch pad) 650 may be coupled to the electronic device600 via a system bus 640 (see FIG. 6B). Additionally, in someembodiments, the keyboard 618 and the mouse 650 may be integrated intoone of the enclosures 612, 614 as shown in FIG. 6A. In other embodimentsthe keyboard 618 and mouse 650 may be external to the electronic device600.

The keyboard 618 and the mouse 650, in one example, may provide userinput to the electronic device 600; this user input may be communicatedto a processor 638 through suitable communications interfaces, buses andthe like. Other suitable input devices may be used in addition to, or inplace of, the mouse 650 and the keyboard 618. For example, in someembodiments the electronic device 600 may be a smart phone, tabletcomputer or the like and include a touch screen (e.g., a capacitivescreen) in addition to or in replace of either the keyboard 618, themouse 650 or both. An input/output unit 636 (I/O) coupled to the systembus 640 represents such I/O elements as a printer, stylus, audio/videoI/O, and so on. For example, external speakers may be electricallycoupled to the electronic device 600 via an input/outlet connection (notshown).

The electronic device 600 may also include a video memory 642, a mainmemory 644 and a mass storage 648, all coupled to the system bus 640along with the keyboard 618, the mouse 650 and the processor 638. Insome embodiments, main memory 644 may store an operating system program,which may include instructions for operating electronic device 600.Processor 638 may be configured to execute the operating system program.Processor 638 may be any suitable microprocessor or microcomputer. Themass storage 648 may include both fixed and removable media, such asmagnetic, optical or magnetic optical storage systems and any otheravailable mass storage technology. The system bus 640 may contain, forexample, address lines for addressing the video memory 642 or the mainmemory 644.

The system bus 640 also may include a data bus for transferring databetween and among the components, such as the processor 638, the mainmemory 644, the video memory 642 and the mass storage 648. The videomemory 642 may be, for example, a dual-ported video random access memoryor any other suitable memory. One port of the video memory 642, in oneexample, is coupled to a video amplifier 634 which is used to drive adisplay screen 616. The display screen 616 may be any type of screensuitable for displaying graphic images, such as a liquid crystaldisplay, cathode ray tube monitor, flat panel, plasma, or any othersuitable data presentation device. Furthermore, in some embodiments thedisplay screen 616 may include touch screen features, for example, thedisplay screen 616 may be capacitive. These embodiments allow a user toenter input into the display screen 16 directly.

The electronic device 600 also may include a communication interface 646coupled to the system bus 640. The communication interface 646 providesa two-way data communication coupling via a network link. For example,the communication interface 646 may be a satellite link, a local areanetwork (LAN) card, a cable modem, and/or wireless interface. In anysuch implementation, the communication interface 646 sends and receiveselectrical, electromagnetic or optical signals that carry digital datastreams representing various types of information.

Code and/or other information (e.g. an operating system program)received by the electronic device 600 may be executed by the processor638 as the code is received. Code may likewise be stored in the massstorage 648, or other non-volatile storage for later execution. In thismanner, the electronic device 600 may obtain program code in a varietyof forms and from a variety of sources. Program code may be embodied inany form of computer program product such as a medium configured tostore or transport computer readable code or data, or in which computerreadable code or data may be embedded. Examples of computer programproducts include CD-ROM discs, ROM cards, floppy disks, magnetic tapes,computer hard drives, servers on a network, and solid state memorydevices.

The electronic device 600 may also include an audio transducer 626. Theaudio transducer 626 may be coupled to the system bus 640, which may inturn electrically connect the audio transducer 626 to any of theprocessor 638, main memory 644, mass storage 648 and the like. The audiotransducer 626 is an output device that produces sound waves in responseto electrical signals. The audio transducer 626 may be encased within orotherwise affixed to one of the enclosures 612, 614 and may be usedalone or in combination with other output devices (such as an externalspeaker) to produce sound. Additionally, the audio transducer assembly626 may mechanically vibrate other surfaces, such as the enclosures 612,614 and/or a supporting surface on which the device rests, to produce alouder sound. Thus, as the audio transducer 626 responds to theelectrical signal it vibrates the enclosure 612, 614, which in turndisturbs air particles and produces sound waves.

FIG. 7 will now be described and embodiments discussed with respectthereto. FIG. 7 illustrates an exploded view of the bottom enclosure612, showing certain elements of the aforementioned computer device(although some are omitted for clarity). Although audio transducer 626is shown installed in bottom enclosure 612, it may also be installed inthe upper enclosure 614. In certain embodiments, the lower enclosure 612may include a top panel 728 and a bottom panel 752. The top panel 728may form the top surface of the bottom enclosure 612 and, in someembodiments, surround the keyboard 618, mouse 650, touch screen (notshown) or other input device, and the like. The bottom panel 752 mayform the bottom surface of the bottom enclosure 612 and electronicdevice 600. Typically, the top panel 728 forms the top surface of theenclosure and may provide access to the keyboard 618 and/or mouse 650.In tablet-style devices, there may be a single enclosure defined by thetop and bottom panels.

The enclosures 612, 614 may be constructed out of a variety of materialsand, depending on the type electronic device 600, may be constructed ina variety of different shapes. In some embodiments, the enclosures 612,614 may be constructed out of carbon fiber, aluminum, glass and othersimilar, relatively stiff materials. The material for the enclosures612, 614 in some embodiments may improve the sound volume and/or qualityproduced by the audio transducer 626. This is because in someembodiments the enclosure 612, 614 mechanically vibrates due tovibrations produced by the audio transducer 626, producing sound waves.Thus, the material may be altered to be more responsive to thevibrations and/or more easily move, increasing the sound quality/volume.Additionally, it should be noted that the bottom enclosure 612 and thetop enclosure 614 may be constructed out of different materials fromeach other. Furthermore, in some embodiments the electronic device 600may only include one of the enclosures 612, 614. For instance, if theelectronic device display 616 includes a touch screen or other displaydevice that also accepts input, then the bottom enclosure 612 may beomitted as the keyboard 618 and mouse 650 may be integrated into the topenclosure 614.

The enclosures 612, 614 in some embodiments may be water and/orair-tight. This is because the audio transducer 626, as discussed inmore detail below, may not require an air-opening (e.g., a grille orscreen) in order for a user to hear sound waves produced by the audiotransducer 626. The audio transducer 626 uses the enclosures 612, 614and/or supporting surface to produce sound waves, as opposed to adiaphragm within a traditional speaker that must be open to the air inorder for the sound waves to be heard. Therefore, the enclosures 612,614 and thus the electronic device 600 may be completely sealed fromwater and/or air. This may permit the electronic device 600 to bewaterproof, more versatile, and allows the electronic device 600 to havea refined, smooth outer appearance. However, as the electronic device600, may include a combination of an audio transducer 626 and a speaker620, in other embodiments the enclosures 612, 614 may include agrill/screen.

The bottom panel 752 and the top panel 728 may be connected together ina variety of ways. In the embodiment illustrated in FIG. 7, the toppanel 728 and the bottom panel 752 are attached via fasteners 725. Thefasteners 725 may be inserted in apertures 727 on both panels 728, 752.Additionally, in some embodiments the fasteners 725 may be used toattach the feet 622 to the bottom panel 752. The top enclosure 614 maybe similarly secured to together, including an upper and bottom panel(not shown). In other embodiments, the enclosures 612, 614 may be gluedtogether or otherwise secured. In still other embodiments, the top panel728 and the bottom panel 758 may include a seal disposed between tocreate a waterproof, air tight connection. The seal helps preventelements from entering into the inner cavity of the enclosures 612, 614when the panels 728, 752 are secured together.

The internal elements described above with regard to FIG. 6B arerepresented by the circuit boards 757, 759, which are shown in arepresentative fashion only. More or fewer circuit boards or othercircuitry may be present and the shape of the boards/circuitry may varyfrom what is shown. The circuit boards 757, 759 may include acombination of the elements described above with respect to FIG. 6B,such as main memory 644, video memory 642, mass storage 648, theprocessor 638 and the like. The circuit boards 757, 759 may beelectrically connected to the audio transducer 626 via the system bus640 or another electrical connection. Furthermore, the circuit boards757, 759 may be secured to the enclosures 612, 614 and enclosed inside.

The audio transducer 626 may be installed in such a manner that one ofthe electromagnet 100 and the attractor plate 110 is attached to the toppanel 728 while the other is attached to the bottom panel 752. In someinstances, the electromagnet 100 may be operably connected to the toppanel 728 while the attractor plate 110 is operably connected to thebottom panel 752, but in other embodiments the electromagnet 100 may beoperably connected to the bottom panel 752 while the attractor plate 110is operably connected to the top panel 728. In still other embodiments,the electromagnet 100 may be connected to a circuit boards 757, 759, forinstance a motherboard, logic board or the like. Thus, in differentembodiments the electromagnet 100 may be connected to either of thepanels 728, 752 or either of the circuit boards 757, 759.

The concepts described here, however, need not be limited to portableaudio devices such as laptop computers. For example, as seen in FIG. 8,the biased electromagnetic transducer may be implemented within a mobilecommunications device 800 such as a smart phone. Mobile communicationsdevice 800 may include an enclosure 802 defining or closing off achamber in which the constituent electronic components of thecommunications device 800 are housed. Enclosure 802 may include a frontor top panel 804 and a rear or bottom panel 806, which are connected bya sidewall portion 808. The top panel 804 may be considered a displayside of the device in that it may include a touch screen display 828that serves as an input and a display output for the device. The touchscreen display 828 may be a touch sensor (e.g., those used in a typicaltouch screen display such as found in an iPhone® device by Apple Inc.).Although the touch screen is illustrated on top panel 804, if desired,it may be mounted on the bottom panel 806 of device 800, on a side wallportion 808 of device 800, on a flip-up portion of device 800 that isattached to a main body portion of device 800 by a hinge (for example),or using any other suitable mounting arrangement. The bottom panel 806may form a back side of the device, which can be held by the user duringoperation of device 800.

To further enable its use as a mobile communications device, device 800may include various acoustic openings or ports at different locationswithin enclosure 802 to allow for transmission of acoustic signals toand from device 800. Representatively, enclosure 802 may have formedtherein a speaker acoustic port 810, a receiver acoustic port 812 andmicrophone acoustic ports 816, 818, 820. Although the acoustic ports areillustrated as separate ports, it is contemplated that any one or moreof the illustrated ports may be combined into one port such that, forexample, the transducers associated with the illustrated receiver ormicrophone ports may instead share the same port. In one embodiment, thereceiver acoustic port 812 is formed within top panel 804 of enclosure802 and speaker acoustic port 810 is formed within an end portion ofsidewall portion 808. It is contemplated, however, that each of theseports may be formed in other portions of enclosure 802, for example,speaker acoustic port 810 may be on the top panel 804 or bottom panel806 while receiver acoustic port 812 is along the sidewall. Each ofthese ports may consist of multiple holes clustered together oralternatively a single, large hole as shown.

Each of the speaker acoustic port 810, receiver acoustic port 812 andmicrophone acoustic ports 816, 818 and 820 may be associated with one ormore transducers, which are mounted within enclosure 802. In the case ofthe microphone acoustic ports 816, 818 and 820, the transducer is anacoustic-to-electric transducer such as a microphone that converts soundinto an electrical signal. The microphone may be any type of microphonecapable of receiving acoustic energy, for example sound through theassociated port, and converting it into an electrical signal. Forexample, in one embodiment, the microphone may be amicro-electro-mechanical systems (MEMS) microphone, also referred to asa microphone chip or silicon microphone. In this aspect, variousfeatures of the microphone such as the pressure-sensitive diaphragm, areetched directly into a silicon chip by MEMS techniques.

Camera 822 may further be mounted to enclosure 802 to capture stilland/or video images of objects of interest. Enclosure 802 may furtherinclude other input-output devices such as an earphone port (not shown)to receive an earphone plug, docking port 814 and command button 826.Docking port 814 may sometimes be referred to as a dock connector,30-pin data port connector, input-output port, or bus connector, and maybe used as an input-output port (e.g., when connecting device 800 to amating dock connected to a computer or other electronic device). Commandbutton 826 may be, for example, a menu button or any other device thatcan be used to supply an input to and/or operate device 800.

A transducer having a magnetically biased electromagnet as previouslydiscussed in reference to FIG. 1A to FIG. 5, may be implemented withincommunications device 800, for example, by operably connecting theelectromagnet 100 and associated coil 120 to the top panel 804 andoperably connecting the attractor plate 110 to the bottom panel 806. Inthis aspect, during operation, the transducer may produce a dynamicforce between top panel 804 and bottom panel 806 such that the bottompanel 806 acts as a diaphragm and vibrates thereby generating soundwaves which can be emitted to the user to enhance an audio performanceof device 800.

While certain embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat the invention is not limited to the specific constructions andarrangements shown and described, since various other modifications mayoccur to those of ordinary skill in the art. For example, although thetransducer assembly (e.g., electromagnet 100 (including coil 120) andattractor plate 110) is described as serving essentially as a“subwoofer,” which enhances a performance of existing speakers withinthe electronic device, the assembly may operate in such a manner that itprovides a near full-range response frequency. For example thetransducer assembly may output both low and mid-range frequencies. Insuch embodiments, the transducer assembly may output not only bass rangefrequencies (e.g., about 20-500 Hz), but also mid-frequencies (e.g.,about 500-1500 Hz or higher). The transducer assembly may therefore becombined with other speakers in an electronic device such as a laptop,tablet or handheld computing device, or used instead of other speakers,to enhance or produce sound which can be output from the electronicdevice to a user without distortion.

Although embodiments described herein have generally been discussed withrespect to standalone electronic devices (many of which may beportable), it should be appreciated that the embodiments disclosedherein may be applied in a variety of other fashions. For example, theaudio transducer described herein may be integrated into conventionalspeakers and operate with the woofers and tweeters of the conventionalspeaker. Likewise, an audio transducer of the type disclosed herein maybe incorporated into a seat or chair as part of a home theaterexperience. The audio transducer may vibrate not only the chair but theperson sitting in the chair under certain circumstances, therebyproviding not only audible but also tactile feedback if desired. Asstill another example, the audio transducer may be combined with acapacitive or touch-based input so that motions of a user's hands on adevice enclosure may act to increase or decrease the output of the audiotransducer. The description is thus to be regarded as illustrativeinstead of limiting.

What is claimed is:
 1. An electronic device comprising: an enclosurehaving a top panel and a bottom panel; an electromagnet mounted withinthe enclosure, the electromagnet having a core portion attached to thetop panel and a coil connected to the core portion; an attractor plateattached to the bottom panel, the attractor plate forming part of amagnetic circuit of the electromagnet such that input of an electricalaudio signal to the electromagnet causes the bottom panel to move andproduce a sound; and a permanent magnet attached to the core portion,the permanent magnet configured to create a bias in the magnetic circuitso as to modify a distortion in the sound.
 2. The electronic device ofclaim 1 wherein the distortion is caused by a rectification of theelectrical audio signal and biasing of the magnetic circuit allows theelectrical audio signal to be recreated as a dynamic force without therectification.
 3. The electronic device of claim 1 wherein the coreportion comprises a coil support arm around which the coil ispositioned, a first side arm and a second side arm, and wherein thepermanent magnet comprises a first magnet and a second magnet, each ofthe first magnet and the second magnet positioned at ends of the firstside arm and the second side arm, respectively, and facing the attractorplate.
 4. The electronic device of claim 1 wherein the core portioncomprises a base portion having a coil support arm around which the coilis positioned, a first side arm and a second side arm extendingtherefrom.
 5. The electronic device of claim 4 wherein the permanentmagnet comprises a first magnet and a second magnet, each of the firstmagnet and the second magnet positioned at ends of the first side armand the second side arm, respectively, and facing the attractor plate.6. The electronic device of claim 4 wherein the permanent magnetcomprises a first magnet and a second magnet, each of the first magnetand the second magnet positioned at sides of the first side arm and thesecond side arm, respectively.
 7. The electronic device of claim 1further comprising: a resilient spacer positioned within the magneticcircuit, between the attractor plate and core portion.
 8. The electronicdevice of claim 7 wherein the resilient spacer comprises a ferromagneticmaterial to improve an efficiency of the magnetic circuit.
 9. Theelectronic device of claim 1 wherein the attractor plate is fixedlyattached to a side of the bottom panel facing the electromagnet.
 10. Theelectronic device of claim 1 wherein the attractor plate comprises aferromagnetic material.
 11. An electronic audio system comprising: anenclosure having a first panel operably connected to a second panel; atransducer mounted within the enclosure, the transducer comprising: anelectromagnet having a core portion mounted to the first panel and acoil positioned around the core portion;; an attractor plate mounted toa side of the second panel facing the first panel, the attractor plateforming part of a magnetic circuit produced by the electromagnet uponinput of an electrical audio signal; and a permanent magnet mounted tothe core portion, the permanent magnet configured to bias the magneticcircuit produced by the electromagnet such that a dynamic force betweenthe first panel and the second panel is proportional to the electricalaudio signal; and a processor in electrical communication with thetransducer and coupled to a memory to execute an operating systemprogram.
 12. The electronic audio system of claim 11 further comprising:a resilient spacer positioned within a gap between the electromagnet andthe attractor plate.
 13. The electronic audio system of claim 11 whereinthe transducer, the memory and the processor are contained within theenclosure.
 14. The electronic audio system of claim 11 wherein thedynamic force between the first panel and the second panel causes thesecond panel to move while the first panel having the electromagnetattached thereto remains substantially stationary.
 15. The electronicaudio system of claim 11 wherein the dynamic force causes one of thefirst panel and the second panel to produce a sound which enhances abass response of the audio system.
 16. A method of outputting sound froman electronic device comprising: generating a sound by producing adynamic force between a first panel and a second panel of an enclosureof an electronic device, wherein producing the dynamic force comprisesapplying an electrical audio signal to an electromagnet having a coreportion and a coil attached to the first panel so as to create amagnetic circuit which attracts the second panel to the first panel; andbiasing the magnetic circuit so that the dynamic force is proportionalto the electrical audio signal.
 17. The method of claim 16 wherein themagnetic circuit is biased by a permanent magnet positioned within themagnetic circuit so as to increase a magnetic force between theelectromagnet and the second panel.
 18. The method of claim 16 whereinthe magnetic circuit is biased using a direct current.
 19. The method ofclaim 16 wherein biasing the magnetic circuit modifies a rectificationof the electrical audio signal so that the sound can be recreated fromthe electrical audio signal without distortion.
 20. The method of claim16 further comprising: an attractor plate attached to a side of thesecond panel facing the electromagnet such that the attractor plate iswithin the magnetic circuit and an attractive force between theattractor plate and the electromagnet pulls the second panel toward thefirst panel.